This invention relates to mild skin cleansers. More particularly, this invention relates to skin cleansers comprising synthetic surfactants, moisturizers, polymeric skin feel and mildness aids and soap.
The cleansing of skin with surface-active cleansing preparations has become a focus of great interest. Many people wash and scrub their skin with various surface-active preparations several times a day. Ideal skin cleansers should cleanse the skin gently, causing little or no irritation, without defatting and overdrying the skin or leaving it taut after frequent routine use. Most lathering soaps, liquids and bars included, fail in this respect.
Synthetic detergent bars, frequently referred to as "syndet bars," are well known and are becoming increasingly popular. However, widespread replacement of soap bars by syndet bars has not so far been possible for a variety of reasons, primarily the poor physical characteristics of syndet bars as compared to soap bars, e.g., smear or bar messiness and lather quality.
Certain synthetic surfactants are particularly mild. However, a major drawback of most mild synthetic surfactant systems when formulated for skin cleansing is poor lather performance, when compared to the highest bar soap standards (bars which are rich in coconut soap and superfatted). On the other side, the use of known high sudsing anionic surfactants with lather boosters can yield acceptable lather volume. Unfortunately, however, the highest sudsing anionic surfactants are, in fact, poor in clinical skin mildness. Surfactants that are among the mildest, such as sodium lauryl glyceryl ether sulfonate, (AGS), are marginal in lather. It will be appreciated that these two factors make the surfactant selection, the lather and the skin feel benefit formulation process, a delicate balancing act.
Similarly, optimization of bar firmness also requires a delicate balancing act with respect to maintaining acceptable lather and mildness, although as a single variable, bar firmness is accomplished through a fairly straightforward process with adjustments to levels of fillers, binders, etc., such as free fatty acids.
It is known that moisturizers provide skin conditioning benefits. For example, it is known that glycerin and/or free fatty acids are added to bars or liquid cleansing products for skin benefits.
Likewise, polymeric skin feel aids are known to those knowledgeable in the art for providing unique tactile characteristics to both the lather and the skin during rinsing.
For background, examples of liquid cleansing compositions are disclosed in the following references. U.S. Pat. No. 4,338,211, Stiros, issued July 6, 1982, discloses liquid skin cleanser with 2.3% to 3% AGS, the polymer JR-400 and small amounts of free fatty acid plus a fatty acid alkylolamide as lather boosting agents. Compositions containing the surfactants AGS and sarcosinate are not disclosed. Also, U.S. Pat. No. 4,491,539, James J. Hoskins and Adriaan Kessler, issued Jan. 1, 1985, discloses liquid cleansing products comprising about 5% to 30% of surfactant, about 0.1% to about 1.0% of guar material, about 0.15% to about 1.0% of nonionic carboxyvinyl polymer, and water. Exemplary compositions containing mild surfactants in general and, specifically, the surfactants AGS and sarcosinate are not disclosed. Another background reference is British Pat. No. 2,103,236A, Colgate, Feb. 16, 1984, which discloses a liquid detergent containing guar gum, a ternary surfactant mixture including betaine. AGS is not used.
U.S. Pat. No. 2,894,912, Geitz, issued July 14, 1959, for "Isethionate Detergent Bar," discloses a detergent bar consisting essentially of from 30-70% of water-soluble alkali metal detergent salts of esters of isethionic acid with mixed aliphatic fatty acids having from 6 to 18 carbon atoms and an iodine value of less than 20, of which mixed acids at least 75% have from 12 to 18 carbon atoms and up to 25% have from 6 to 10 carbon atoms, from 2-10% of at least one water-soluble suds-boosting detergent salt selected from the group consisting of alkali metal and organic amine higher aliphatic fatty alcohol sulfates, alkyl aryl sulfonates, and higher aliphatic fatty acid taurides, from about 1% to about 9% water, from about 2.5% to about 25% of water-soluble higher fatty acid soap, and from 10-40% of at least one higher fatty acid having from about 12 to about 25 carbon atoms as a binder and plasticizer, said bar having a pH within the range from 6 to 8, measured as a 10% aqueous solution of the bar composition at 35.sub.-- C. This patent does not teach the use of polymeric skin feel aids nor the use of other mild synthetics.
U.S. Pat. No. 4,234,464, Morshauser, issued Nov. 18, 1980, for "Detergent Bar Composition and Binder Therefor," discloses a detergent bar in Example 6 which comprises: 45% sodium cocoyl isethionate, 5% alkyl amide, 37.5% stearic acid, 5.0% hydrogenated tallow glycerides, and 1% Polymer JR. Morshauser teaches that his detergent bars can contain up to 5% soap "without substantial detriment." This patent also teaches the use of up to 1.5% cationic polymer.
U.S. Pat. No. 4,012,341, Orshitzer et al., issued Mar. 15, 1977, for a "Unique All Synthetic Detergent Shampoo Bar," discloses a bar comprising a mixture of anionic and nonionic detergents. Examples 2 and 4 use 1% JR-400 in bars primarily based on sodium lauryl sulfate, which is an unacceptable surfactant for the present invention.
U.S. Pat. No. 3,761,418, Parran, Jr., issued Sept. 25, 1973, for "Detergent Compositions Containing Particle Deposition Enhancing Agents," discloses detergent compositions including a bar which contains 1% JR-400. However, the main surfactant is alkyl sulfate, which is unacceptable for the mild skin cleanser of the present invention.
Thus, in view of the above, it will be appreciated that rather stringent requirements for skin cleansers limit the choice of surface-active agents and final formulations represent some degree of compromise. Mildness is often obtained at the expense of effective cleansing and lathering. Conversely, mildness may be sacrificed for either preferred lathering characteristics, bar firmness, product stability, or all of these.